Switch jaw and latch construction



March 13, 1956 w. GRAYBILL SWITCH JAW AND LATCH CONSTRUCTION 4 Sheets-Sheet 1 Filed Oct. 20, 1952 March 13, 1956 H. w. GRAYBILL SWITCH JAW AND LATCH CONSTRUCTION 4 Sheets-Sheet 2 Filed 001.- 20, 1952 gill IN VEN TOR. #0046) ?94 lrmmm 4 Sheets-Sheet 5 E m N N m mN N H. W. GRAYBILL SWITCH JAW AND LATCH CONSTRUCTION March 13, 1956 Filed Oct. 20, 1952 IN V EN TOR. 14 04/469 M 694x47 aid-n3 3W March 1956 H. w. GRAYBILL SWITCH JAW AND LATCH CONSTRUCTION 4 Sheets-Sheet 4 Filed Oct. 20. 1952 I IN V EN TOR. x; fiewa can? 9M United States 2,738,402 SWITCH JAW AND LATCH CONSTRUCTION Howard W. Graybill, Greensburg, Pa., assignor, by me sne assignments, toI-T-E Circuit Breaker Company, Philadelphia, Pin, a corporation of Pennsylvania Application October 20, 1952, Serial No. 315,619 13 Claims. (Cl. 200-169) My invention relates to disconnecting switches and The disconnect switch of my invention is of a high voltage hook stick operated type having one or more blades rotatably mounted at a hinged terminal of the switch. The switch blades are rotated into and out of engagement with a second terminal usually referred to as a breath jaw or jaw terminal, to close and open the switch. This operation is usually accomplished from a remote point by means of a hook stick which engages a pull ring .at the jaw terminal end'ofthe switch blade. In switches of this type, it is desirable to have a positive latch to lock the switch blades in closed position to insure that they will not open due to the stresses set up by a short circuitor fault condition or due to any other accidental cause. J I

,Heretofore, short circuiting latches of the type to which my invention is related were complicated and undepeiidable devices. For example, the prior art short circuited latching means usually required a plurality oisprings, latches and moving parts resulting in a device .whichQWas relatiyely expensive and undependable due to its multiplicity of parts. Furthermore, these latching means were constructed in a manner which did not permit the ,easy breaking of ice formation which frequently resulted in in'efii'cient operation of the switch.

I propose to provide a novel latch and latch disconnect means with .a minimum number of parts and movingunits to insure reliability of operation with a minimum cost.

In my novel latch disconnect means, I provide a unitary latch-member permanently mounted at the jaw end of the disconnect switch. The latch member has a plurality of latching surfaces for engagement with inwardly extendingindentatiOuS of the switch blades when the disconnect switch is-in closed position. I

Ihe latch member is also provided with-a flat surface whichwillbe engaged by a pull ring pry outfinger as described below. A pull ring is pivotally mounted at the jaw end on switch blades and. is provided with an eyelet on one side of the pivot and a pry out finger at the opposite side: thereof. 7

The switch blades are provided with inwardly extending cammedsurfaces positioned beneath the pry out finger of the pull ring. 7 g

The switch is opened by a single continuous upward pull on the pull ring which forces the pry" out finger thereof down between the cammed surfaces of the blade and forces them apart until the indentations ofthe switch blade clear the latching surfaces of the latch" means. At this time, the pull ring pry out finger strikes the" flaft surface of the latch member, giving the opratoi-a' two to one mechanical advantage to further facilitate the opening of the blade. Thus," it is possible to disengage the short eireuited latch and open my novel disconnecting switchwitli'asingle 2,738,402 Patented Mar. 13, 1956 2 continuous motion of the single moving part, namely the pull ring".

Accordingly, it is a primary object of my invention to provide, a novel short circuit latch .and latch disconnect means for a disconnect switch in which a single continuous motion of the latch disconnect means disehgages the latch and is instrumental in opening the switch.

' Another object of my invention is to provide a short circuit latch means with a minimum numberoi parts.

A still further object of my invention is to provide a latch and manual means which is simple in construction andeconomical to manufacture.

Still" another objectof my invention is to provide a novel arrangement wherein a pull ring with a two to one mechanical advantage can be used to break ice or corrosive seals between the blade member and the break wflglie- A further object of my invention is-to provide a novel short circuit latch which can be disengaged by the same single continuous motion used to open the disconnect switch, I

Thesean'd other objects ofmyinvention will be apparent from the following description when taken in connection with the drawings in which: t p

Figure 1 is a side view of my novel disconnecting switcmmounted on a frame and showing same inclosed position with heavy line and in open position with dotted line's.

Figure 1a is an enlarged side view'of the disconnect switch showing the hinged terminal, blade assembly and jaw terminal;

Figure 2 is atop view of Figure 1.

Figure 3 is a view taken along the line of Figure 1a and shows the engagement of the spherical radius contacts of the switch blade with the break tongue and the cantilevered stress on the spring contacts.

Figure 4 is a view taken along the 1ine'4-,4' .of-Figure 1a and shows the engagement of the switch blades with the. short circuited latch.

, Figure 5 is a top view of the switch blades used in my switch and illustrates the novel spherical radiuscoritacts which are formed therein, the indentations .of blade forlatching engagement with the short circuit latch; and the". inwardly protruding cam surfaces.

Figure 6 is a side view of the switch blade-oi Figurefi.

Figure 7 is a view taken along the li-ne 7+-'7 of Figure 6 showing the details of the spherical radius contact's and the cammed surface for separation of the'bladesby means ofthe pull ring. a

Figure 8 is a view taken along the line 8+8 of Figure 5 showing a side view of the cammed surfaces of the switch blade.

Figure 9 is a view taken along the lines '9-'-9 of Figure -5 showing the indented upper portion of the switch blade for engagement with the short circuiting latch.

Figure 10 is a perspective view showing'the jaw end of my novel disconnecting switch.

Referring to Figure 1, the insulator units 10 and 11 are mounted on the base 12 by means of bolts 13. The upper ends of the insulator units 10 and 11 support the terminal contacts 14 and 15 which are attached thereto by means of bolts 17 and- 18. The terminal connector 14 is provided with a horizontal extension 16 in which openings 17 andltl are provided to permit connection of the electrical thereto.

A'vei-tical extension 19 of the terminalf connector lfl has the hinge ends of the blades 30 and 31rotatably mounted thereon by means of pin 32. The terminal connector 15 located at the jaw end of the disconnecting switch is provided with horizontal extensions li and 34 in which openings 35 and 36 are'provided for proper connection tothe line.

As best seen in Figures 1, 1a, 3 and 10, the terminal connector 15 has a vertical extension 40 which forms the break tongue of my novel disconnecting switch. The entire terminal connector 15, comprising the horizontal extensions 33 and 34 and the vertical extension 40 may be a copper casting with the vertical sides of the break tongue 40 machined to obtain parallel finished surfaces.

It is necessary to machine the sides 40a and 40b of the break tongue 40:

(1) So that they are parallel and have smooth surface for proper electrical engagement with the spherical radius contacts;

(2) To provide a flat surface for the accurately machined spacers 44 and 45 so that the resilient spring contacts 41 and 42 can be properly spaced from the parallel sides. By this means, an accurately predetermined consistent contact pressure can be obtained.

Spring contact arms 41 and 42, as best seen in Figures 3 and 10, are spaced from the break tongue 40 by means of spacers 44 and 45. The spring contacts 41 and 42 and the spacers 44 and 45 are held in position by means of the nut and bolt 4647. The spring contacts 40 and '41 which carry a portion of the current along with the break tongue 40, are made from a high strength, high conductivity precipitation hardened alloy such as beryllium copper which is not subject to annealing at temperatures encountered in the operation of the disconnecting switch. As seen in the figures, the spring contacts 41 and 42 are cantilever mounted so that the contact blade will place a cantilever stress on them when it is closed over and touching the parallel sides of the break tongue 40.

The spacer units 44 and 45 are machined members which accurately position the spring contacts 41 and 42 to control the distance between them and the sides 40a and 40b of the brake tongue 40 are machined finished to insure that these units are smooth and parallel to each other.

As best seen in Figures 3 and 10, the spring contact members 41 and 42 are mounted by means of the bolt and nut 46 and 47 at their lower end so that the engagement of the knife blades 30 and 31 with the break tongue 40, as indicated, will cause a cantilevered stress to be placed on the spring contact arms. By this arrangement, high uniform consistent and predetermined contact pressure is insured.

The break tongue 40, as seen in Figures 1a, 4 and has a step extension 40; a short circuiting latch 50, comprising U-shaped legs 51 and 52 which straddle the step extension 40; and is attached thereto by means of connecting member 53. The short circuiting latch 50 has an upward extending step'section 55 which serves as a step or foundation for the pry out extension 81 of the pull ring 80 as will hereinafter be more fully explained.

The-short circuiting latch member 50 is also provided with a second upwardly extending portion 57 which has a latching portion 58 with step sections 59 and 60. The step sections 59 and 60 of the latch 58 serve to hold the switch blades in engaged position during the occurrence of a short circuit as will hereinafter be more fully explained.

The switch blades 30 and 31 are spaced from each other by means of copper rod 71 and attached to each other by means of copper rivet 70 passed thereto. The switch blades 30 and 31 which are preferably rectangular in shape are formed at their jaw end with- (1) Raised contacts 73, 74, 75, 76, 77 and 78 of spherical radius (a) 73-75 and 76-78 on one side to engage break tongue 40, (b) 74 and 77 on the other side to engage spring contacts 41 and 42;

' (2) Inwardly protruding portions 90 and 91 to form a cammed surface by which the blades can be separated to enable their removal from latch engagement with a short circuited latch 58;

" (3) Indented upper sections 94 and 95 at the jaw end 4 Y in order to enable the blades to be latched by the short circuited latch member 58.

As best seen in Figures 5 and 7, the contacting surfaces 73 through 78 for the switch blade are formed by providing a plurality of spherical radius protrusions having approximately a radius. This spherical radius contact is made by a forming operation on the switch blades 30 and 31 so that no reduced cross-section or constrictions result from their formation.

Thus as seen in Figures 5 and 7, the switch blade 30 is provided with raised contacts 73 and 74, and 75. The raised contacts 73 and 75 protrude approximately on one side of the blade and the raised contact 74 protrudes the same distance from the opposite side of the switch blade. In like manner the switch blade 31 is formed with raised contacts 76, 77, and 78. Thus as seen in Figure 6, the plurality of spherical radius contacts 73, 74, and 75 may be positioned in alignment with the long axis of the switch blade 30. Figure 3, which is a view taken along the line 3-3 of Figure la, and Figure 10, illustrate the manner in which the inwardly protruding spherical radius contacts 74 and 75 engage the break tongue 40 and the manner in which the outwardly protruding spherical radius contacts 74 and 77 engage the vertical extending spring contacts 41 and 42 respectively.

It will therefore be apparent that the engaging area of the inwardly protruding spherical radius contacts 73-75 and 7678 are axially spaced from the outwardly protruding spherical radius contacts 74 and 77 to thereby increase the area of the switch blade which will be exposed to the low excess heating in the event of a short circuit condition. Furthermore, these contact surfaces are provided from the original material of the switch blades 30 and 31 without the necessity of reducing its cross-sectional area and thereby prevent any possibility of heating due to any constriction of the conducting material.

As above noted, the switch blades 30 and 31 are provided with an inwardly extending cammed means 90-91 as seen in Figures 5, 7, 8 and 10. These inwardly extending cammed sections 90 and 91 are positioned to the left of the switch blade connecting studs 92 and 93 as seen in Figures 2 and 6. As will hereinafter be apparent, the cammed means 90 and 91 are provided to enable the pry out blade 81 of the pull ring to wedge therebetween in order to cause a separation of the switch blades 30 and 31 to enable release from the short circuited latch 58.

As above noted, the switch blades 30 and 31 are also provided with inwardly extending indentations 94 and 95 positioned at the upper end thereof near the jaw end of the blade. As best seen in Figures 9 and 10, the indentations 94 and 95 protrude inwardly approximately and as seen in Figure 5 are positioned on the switch blades 30 and 31 between the spherical radius contacts 75-78 and cammed surfaces and 91. The indentations94 and are provided to enable latch engagement between the switch blades 30 and 31 and the latch means 58 as will hereinafter be more apparent.

Referring now to Figures 1, 1a, 2, 3 and 4, and 10, the disconnect switch is shown in the closed position. In this position the inwardly extending identations 94 and 95 at the upper end of the switch blade are positioned under the latching surfaces 59 and 60 of the latch means 58. In this position the lower ends 101 and 102 of the switch blades 30 and 31 are seated on the horizontal ledges 103 and 104 at the lower end of the latch unit 55. Thus it will be apparent that the blades 30 and 31 of the disconnect switch are sandwiched between the latching surfaces 59 and 60 of the latch head 58 and the horizontal ledges 103 and 104 of the latch means 55 to prevent vertical movement thereof. On the occurrence of a short circuit condition, the loop circuit created at the contact points will create an electromagnetic force ess nce to b ow. he swit h bladesrupwardly Ho cv r,. -.dueto t e la ch cnasscmcnt between the inden a 244 m =95 of the switch blades 30 and 31 with thelatch surfaces .59- and 60. of the latch unit 5.8 the disconnect switch blades30 and 31 willremain in closed or latched position.

The manner in which the switchwblades 30 and 31 are moved from the closed position of Figures ,1 la to the open position (indicated by the'dotted lines in Figure 1), will now be described. The -pull; ring80 is pivoted on the pin 92 between the {switch blades and .31 and is provided with a pry out extension 81 positioned between the connecting pins 92 and 93. When the operator desires to open the switch an upward gcqntinuous pulling force is supplied ,to the pull ring-\SQb'y means of a 'hook stick of any other desirable gneans. This causes counterclockwise rotation of. the pull ring Y (2) The pry out finger 81 will engage the snrface of the latch means 55 and thereby be prevented :from further-downward movement thereof.

,As best seen in Figure 1, :the pullring is constructed with approximately a two :to one mechanical adyantage.

Thus, .as the pry .out finger 81 engages the horizontal 1'.

,flat base. 110 of the latch means -55, the pulling force ionthe pull ring 80, which previously resulted in mere rQwflQn 0f the ,ring about the pivot 98, will now IQSlllt in both rotation and upward movement ofthe'pnllring due to the seating of the pry out finger 81 on he hcrizontal switch 110. Hence, by a single continuous motion, the switch blades 30 and 31 can .be moved from the closed posit-1 9 Qf Figure 1 to the open position indicated by the dotted lines. Pin means 92 and 93 are positioned through the switch blades 30 and 31 to limit the movement ot' h pilllr ngfi Accordingly w th this novel la c and p y out mechanism, the switch blade is positively locked in the closed position, and the disconnect switch may be movedto open position with a single ,co,ntinuou,s motion of only (one moving part other th n the bl de mem ers:

Accordingly, in summary, with my novel latch disconnect means, I provide a unitary latch member per- .manently mounted at the jaw end of the disconnect switch.

The latch member has a plurality of latching surfaces for engagement with inwardly extending indentations. of th switch b de wh n th dis nn c itch is in losed posi ion. Th latch mem er s also p vided with a fl t urfac h ch will. be engag d-by a pul n P y out ,fipger as described below, A pull ring is pivotally mountedat the jaw end on switch blades and is provided with an eyejlet on one side of the pivot at a pry out finger on the opposite side thereof,

Theswitch blades are provided with inwardly extendfing cammed surfaces positioned beneath the pry out finger of the pull ring. To open the switch, a single continuous upward pull on the pull ring forces: the pry out finger thereof down between the cammed suriaces of the blade and forces them apartuntil the indentations ,of the switch blade clear the latching surfaces of the latch" means. At this time, the pull ring pry out finger strikes the fiat surface of the latch member, giving the operator a two to one manual advantage to further facilitate-"the opening of the blade. Thus, it'ispossihle to'di'sen'gage the short circuited latch andopen niy novel disconnecting switch with a single continuous motion of a single moving part, namely the pull ring.

Fu herm re, the single tri on of my lat hperrnit easy removal and breakage of any ice which'may' fdrm thereon;

all)

1n ithefcregoing, I have described my inventi n in connection with prefer-red vemobirnents thereof.

Many yaniations and modifications of the principle of my 'nyention within the scope of-the drawings are herein b 0.11s. Accordingly, I prefer to .be ,boundfinot by the sp cg s: disclosure herein but only bythe appending cla msd s i 1 in. a:,disconnecting switch having a first terminal and .a jaw terminal, a switch blade movably mounted on first ,terminal, said switch blade positioned for contact engagementand disengagement with said jaw :termi- .nal, said switch blade having indentations. at 'the upper portion of the jaw end thereof and inwardly extending .cammed surfaces in the sides near the jaw end thereof; ,a-laitch member permanently secured to the jaw end of said disconnect switch, said latch member havinga-latcliing surface and a flat base, a pivotally mounted pull ring-comprising an eyelet and a pry out finger, said pull ring movably mounted on said switch blade at the jaw end thereoi, said indentations of said switch bladeengagsaid latching surfaces of said latch means, rotation of'said pry out finger of said pull ring engaging said cannned surfaces to disengage said identationsfrom said latched surfaces and engaging said flat base of said latch means'to eflect disengagement of said switch blade from said jaw tend.

In a disconnecting switch having. a first terminal and a jaw terminal, :a switch blade movably mounted at said first terminal, said switch blade positionedgfor contact engagement .and disengagement with .said jaw terminal, said switch blade having a latch and inwardly extending .ca-mmed surfaces .at one end thereon-a. latch member permanently secured to the jaw terminal, said latch member having a ,pair of latching surfaces and .a fiatbase, a pit/orally mounted pull ring comprising an .eyclci nd, a pry ut fing r, said p l ring pivotally mountedlat said one endlof said switch blade, said latch of said switch blade engaging said latching surfaces of said latch" ,means, rotation of said pry .out finger of said P1 1 ring. engaging said camrned surfaces to disengage aid latch from said latched surfaces and enga ing said flat base of said latch means to effect disengagement of said switch blade from said jaw terminal, said pull ring having ,a two to-oneadyantage to enable easy open .ing of said disconnect switch when said pry out finger engagessaid fiat base,

3. In a disconnecting switch havin ,a hinged terminal and a jaw terminal, a pair of. switchblades movably mounted on said hinged terminal, said switch blades:p.0- sitioned for contact engagement and disengagementwith said jaw terminal, said switch blades ha ingindentations at the upper portion of the jaw end thereof-and inwardly extending. cammcdsurfaces in the sides :near the jaw end thereof;-a latch member permanently secured to the jaw end of said disconnect switch, said latch member having a pair of latching surfaces and a flat base, a piyotally mounted pull ring comprising an eyelet and a pryout finger, said. pull ringpivotally mounted between ,saidswiteh blades at the jaw end thereof; said indentations of said switch blade engaging said latching surfaces of said. latch means, rotation of said pry out finger of said pull ring engaging said cammed ,surfacesto disengage base of said latch means to effect disengagement of said switch blades from said jaw terminal said switch blades positively locked inclosed position by engagement of said indentations with said latching surfaces.

.4, in a disconnecting switch having a first terminal and a jaw terminal, aswitch blade movably mounted at said first terminal, said Switchblade positioned for contact engagement and disengagement with said jaw terminal, said switch blade having a latch and cam .rneansatjone end thereof, a latch member permanently secured to the jaw terminal'of said disconnect switch, said latch member having a latching surface and'a flat base, a movably mounted pull ring comprising an eyelet and a pry out blade at the jaw end thereof, said latch of said switch blade engaging said latching surfaces of said latch means, rotation of said pry out finger of said pull ring engaging said cam means to disengage said latch from said latch surfaces and engagement of said flat base of said latch means by said pry out finger effecting disengagement of said switch blade from said jaw terminal; said pull ring having a two to one advantage to enable easy opening of said disconnect switch when said pry out finger engages said fiat base; said engagement of said pry out fingers with said cam means effecting disengagement of said latch from said latch member.

5. In a disconnect switch comprising a hinge end, a jaw end and a pair of switch blades, said switch blades rotatably mounted at said hinge end and positioned for engagement and disengagement with said jaw end and having a latch permanently mounted thereon, said jaw end of said disconnect switch having latch means, said latch engaging said latch means when said switch blades are in engaged position, inwardly extending cammed means at the jaw end of said switch blades, manually operable means for engagement with said cammed means to remove said latch from said latch means, said manually operable means connected to cause disengagement of said switch blades with said latch means and to cause disengagement of said switch blades with said jaw terminal with a single continuous motion thereof.

6. In a disconnecting switch having a first terminal and a jaw terminal, a switch blade movably mounted at said first terminal, said switch blade positioned for contact engagement and disengagement with said jaw terminal, said switch blade having a latch and cam means at one jaw end thereof, a latch member permanently secured to the jaw terminal of said disconnect switch, said latch member having a latching surface and a flat base, a movably mounted pull ring comprising an eyelet and a pry out finger, said pull ring movably mounted on said switch blade at the jaw end thereof, said latch of said switch blade engaging said latching surface of said latch member, movement of said pry out finger of said pull ring engaging said cam means to disengage said latch from said latched surface and engaging said flat base of said latch member to effect disengagement of said switch blade from said jaw terminal, said pull ring having a two to one advantage to enable easy opening of said disconnect switch when said pry out finger engages said flat base; said pull ring causing disengagement of said latch with the latching surface of said latched member and disengagement of said switch blade with said jaw terminal with a single continuous motion thereof.

7. In a disconnecting switch having a first terminal and a second terminal, a pair of switch blades movably mounted at said first terminal, said switch blades positioned for contact engagement and disengagement with said second terminal, said switch blades having indenta tions at the upper portion at the second terminal end thereof and inwardly extending cammed surfaces on the sides at the second terminal end thereof, latch means to engage said indentations when said switch blades are in engagement with said second terminals of said disconnect switch and means co-acting with said cammed surfaces to disengage said indentations from said latch means at the initiation of switch blade movement to 'c'o'ritact disengagement and to simultaneously relieve contact pressure.

8. In a disconnecting switch having a hinged terminal and a jaw terminal, a pair of switch blades movably mounted on said hinged terminal, said switch blade posiend thereof; said switch blades having a pull ring movably mounted therebetween at one end thereof, said latch engaging a latch means when said disconnect switch is in closed position; said pull ring cooperating with said cammed surface to disengage said indentations from said latch means at the initiation of switch blade movement to contact disengagement and to simultaneously relieve contact pressure.

9. In a disconnecting switch having a hinged terminal and a jaw terminal, a pair of switch blades rotatably mounted on said hinged terminal, said switch blades positioned for contact engagement and disengagement with said jaw terminal, said switch blades having indentations at the upper portion of the jaw end thereof and inwardly extending cammed surfaces in the sides near the jaw end thereof; a latch member permanently secured to the jaw end of said disconnect switch, said latch member having a pair of latching surfaces and a flat base, a pivotally mounted pull ring comprising an eyelet and a pry out finger, said pull ring pivotally mounted between said switch blades at the jaw end thereof, said indentations of said switch blades engaging said latching surfaces of said latch means, rotation of said pry out finger of said pull ring engaging said cammed surfaces to disengage said indentations from said latched surfaces and engaging said fiat base of said latch means to effect disengagement of said switch blade from said jaw end.

10. In a disconnecting switch having a hinged terminal and a jaw terminal, a pair of switch blades rotatably mounted on said hinged terminal, said switch blades positioned for contact engagement and disengagement with said jaw terminal, said switch blades having indentations at the upper portion of the jaw end thereof and inwardly extending cammed surfaces in the sides near the jaw end thereof, a latch member permanently secured to the disconnect switch at the jaw terminal, said latch member having a latching surface and a flat base, a movably mounted pull ring comprising an eyelet and a pry out finger, said pull ring mounted on said switch blades at the jaw end thereof, said indentations of said switch blades engaging said latching surfaces of said latch means, rotation of said pry out finger of said pull ring engaging said cammed surfaces to disengage said indentations from said latched surfaces and simultaneously relieve contact pressure, and engaging said flat base of said latch means to effect disengagement of said switch blades from said jaw terminal, said pull ring having a two to one advantage to enable easy opening of said disconnect switch when said pry out finger engages said fiat base.

ll. In a disconnecting switch having a hinged terminal and a jaw terminal, a pair of switch blades rotatably mounted at said hinged terminal, said switch blades positioned for contact engagement and disengagement with said jaw terminal, said switch blades having indentations at the upper portion of the jaw end thereof and inwardly extending cammed surfaces in the sides near the jaw end thereof, a latch member permanently secured to the jaw end of said disconnect switch, said latch member having a pair of latching surfaces and a flat base, a pivotally mounted pull ring comprising an eyelet and a pry out finger, said pull ring pivotally mounted between said switch blades at the jaw end thereof, said indentations of said switch blade engaging said latching surfaces of said latch means, rotation of said pry out finger of said pull ring engaging said cammed surfaces to disengage said indentations from said latch surfaces and engaging said flat base of said latch means to effect disengagement of said switch blade from said jaw end; said pull ring having a two to one advantage to enable easy opening of said disconnect switch when said pry out finger engages said fiat base.

12. In a disconnect switch comprising a hinge end, a jaw end and a pair of switch blades, said switch blades rotatably mounted on said hinge end and positioned for engagement and disengagement with said jaw end, said switch having a latch means permanently mounted thereon, said jaw end of said switch blades having indentations for engagement with said latch means when said switch blades are in engagement with said jaw terminal, inwardly extending cammed means at the jaw end of switch blades, manually operable means for engagement with said cammed means to remove said indentations from latch engagement with said latch means, said manually operable means connected to cause disengagement of said switch blades with said latch means and to cause disengagement of said switch blades with said jaw terminal with a single continuous motion thereof.

13. In a disconnecting switch having a hinged terminal and a jaw terminal, a pair of switch blades rotatably mounted on said hinged terminal, said switch blade positioned for contact engagement and disengagement with said jaw terminal, said switch blade having indentations at the upper portion of the jaw end thereof and inwardly extending cammed surfaces in the sides near the jaw end thereof, a latch means permanently secured to the jaw end of said disconnect switch, said latch means having a pair of latching surfaces and a flat base, a pivotally mounted pull ring comprising an eyelet and a pry out finger, said pull ring pivotally mounted between said switch blades at the jaw end thereof, said indentations of said switch blade engaging said latching surfaces of said latch means, rotation of said pry out finger of said pull ring engaging said cammed surfaces to disengage said indentations from said latched surfaces and engaging said flat base of said latch means'to effect disengagement of said switch blade from said jaw end, said pull ring having a two to one advantage to enable easy opening of said disconnect switch when said pry out finger engages said flat base; said pull ring causing disengagement of said indentations with the latchingsurfaces of said latched means and disengagement of said switch blades with said jaw terminal with a single continuous motion thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,337,105 Templeton Apr. 13, 1920 1,819,779 Hoye Aug. 18, 1931 1,878,377 Christensen Sept. 20, 1932 1,966,894 Jacobs July 17, 1934 

